GRC Projects

DALSTON SQUARE

Interest from potential purchasers, due to the location and eye-catching design, was already high. The project was always destined to progress at breakneck speed. Therefore the guaranteed availability of vast quantities of GRC cladding panels when needed – together with swift, trouble-free installation – was emphasised to GB Architectural (GBA) as being of paramount importance.

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Pre-design

Technical teams from GBA, façade contractor M Price and developer Barratt first devoted their energies toward the finalisation of a fixed-project cost and preparing large-scale samples for planning approval. Alongside this, close liaison continued with the NHBC, as impact/weather testing, panel configuration and jointing details were progressed.

The high-rise contemporary residential buildings were originally to have been constructed using traditional precast concrete panels. The developer wanted to reduce the construction programme, reduce the loadings upon the structure and remove the need for tower cranes. At the same time it still demanded a highly durable, best-quality Portland finish.

Advantages

Grade 18 GRC cladding was the ideal solution. Among its advantages, is its light weight; this high-performance, thin-section composite concrete product typically weighs 70kg/m2.

The installation process for panels negates the need for site craneage and external scaffolding. It is totally unaffected by inclement weather and, in the main, is completely removed from the project critical path. The design methodology followed tried and tested principles, which facilitated fast, simple, effective connection details. This removed the need for any secondary carrier system.

Routine maintenance of the panels, once installed, is virtually non-existent.

Further highly significant factors leading toward the ultimate selection of Grade 18 GRC cladding are the inherent environmental and sustainability benefits, in particular the product’s BREEAM A+ rating.

The selection of GRC is – at 15,000m2 in total – the largest volume residential GRC cladding scheme ever undertaken in the UK.

Design

In December 2009, GBA’s Grade 18 Portland LSB GRC cladding panels were formally approved for use and detailed design work began.

For the detailed design, co-ordination and interfaces process, in-house design staff of all parties collaborated closely to create all the panel designs, restraint designs, flashings, interface and sequencing details. This ensured that the installation of this open rain screen cladding solution would unfold smoothly and seamlessly.

John Crosby of Smart Crosby International says, “The main design challenge was to accommodate the stiffening of the GRC elements and fixing systems within the slender cladding zone required by the architects.

The GRC cladding also had to interface with other cladding materials, flashings and supporting structure in order to provide a suitably drained open rain screen. The design freedom and mouldability offered by GRC during manufacture was well suited to the complexity of such interfaces, while enabling the finished cladding to provide the appearance of traditional precast concrete.”

The designs for the North Blocks were finally signed off in June 2010 with the first panels then being placed into manufacture in August 2010. To ensure that adequate panel quantities and types were available in sequence and precisely when needed, GBA devoted several weeks’ advance production almost exclusively to Dalston Junction’s GRC requirements. More than 3000m2 of panels were produced, quality checked and packaged, then held within GBA’s secure storage compound ahead of the commencement of first deliveries.

Just-in-time delivery

Due to site access and storage constraints, GBA agreed to provide daily just-in-time deliveries, these taking place on either articulated or small (rigid body) vehicles dependent upon site logistics at the particular point in the project. Installation of the Grade 18 GRC cladding began in late November 2010.

The entire North Blocks GRC cladding installation (completely unaffected by the memorable December 2010 big freeze) was completed within five months.

Following almost 12 months of constant collaboration and co-operation, the Dalston Junction North Blocks have undoubtedly proved a success. The project was completed on time and for exactly the agreed fixed lump-sum budget cost. All of the GRC panels are clean and crisp, requiring virtually no ongoing maintenance. As a result, the properties look stunning, sales are buoyant and the South Blocks construction programme has been accelerated to meet demand. The South Blocks GRC cladding installation started in March.

Blocks S5 and S6 of the South Blocks are now completed. The remaining South Blocks (S1–S3) are all concurrently under construction, with completion due in early 2013.

A further brand new phase of works (2000m2+) has recently been added, namely ‘Dalston Cottages’. Installation of this starts in January 2013 and completes in April of that year.

Challenged

Colin Chapman of M Price concludes, “In the current market we find ourselves continually challenged by our clients to deliver projects within ever tighter timescales. Also to assist in getting the project started by tackling budgetary issues head-on and working with our clients’ technical teams to deliver real-life and viable value engineering options. This was undoubtedly achieved on the project at Dalston.”